Functional and biochemical alterations in the rabbit urinary bladder following ileocystoplasty

Although the use of ileocystoplasty has increased significantly in recent years, very little is known concerning the smooth muscle properties of the implanted bowel segment. In a previous study, preliminary evidence was presented which indicated that the pharmacological response of the cytoplastic ileal segment to autonomic agonists changed toward that of the bladder. The present study extends and expands these preliminary observations on the physiology and pharmacology of augmentation cystoplasty. Augmentation cystoplasty with detubularized ileum was carried out in 16 rabbits. In vivo and in vitro physiological and pharmacological studies were carried out one and three months after surgery. The results can be summarized as follows: 1) in-vivo CMG at one month was similar to that of the preoperative bladder, but at three months there was a 24% increase in capacity, with the presence of multiple phasic contractions beginning at a volume of approximately 65% of capacity. 2) The frequency and magnitude of spontaneous activity in the cystoplastic ileum did not significantly alter from that of the normal ileum. 3) Cystoplastic ileum responded to muscarinic stimulation differently from the normal ileum. The bladder responded with an increase in the tension whereas the ileum responded with an increase in the frequency and amplitude of phasic contractions. The cystoplastic ileum responded with a pronounced sustained contraction with phasic contractions superimposed. The tonic contraction at three months was of a significantly greater magnitude than that at one month. 4) The qualitative and quantitative response to field stimulation of the cystoplastic ileum was altered from that of the ileum towards that of the bladder. 5) The normal bladder contains greater amount of creatine phosphate and lesser amounts of creatine than the normal ileum. Cystoplasty, after three months induced a change in the ileal segment towards the bladder (increased creatine phosphate and decreased creatine). 6) The normal ileum was found to have greater number of muscarinic receptors than the normal bladder whereas the cystoplastic ileum at three months was intermediate.